The aim of this project is to investigate the efficacy and rationale of immunotherapy with BCG organisms and leukemia cell vaccines as an adjunct to chemotherapy of human leukemia. Non-specific immune competence and specific tumor immunity will be monitored both by in vivo delayed hypersensitivity testing and by in vitro tests for humoral antibody and lymphocyte reactivity. These investigations will study the development of specific anti-tumor immunity in relation to the progression of the neoplastic disease and the underminding of its effects by immunosuppressive chemotherapeutic agents.